1. Field of the Invention
The present invention relates generally to a device for ensuring the smooth shifting of a strand from a full reel to an empty reel in a strand winding machine and more particularly to improvements in the snaggers provided on the wheels which are rotating with the two associated reels arranged parallel to each other.
2. Description of the Prior Art:
In order to shift a strand from a full reel to an empty reel in a winding machine, it is generally practiced to provide snaggers, designed to catch and grip the strand, at the periphery of each wheel rotating with its corresponding reel. There is also a mechanism known such that when the wheel is rotation, the snaggers thereon are actuated to grip the strand by utilizing centrifugal force created by rotation of the wheel, and this gripping of the strand by the snaggers is released when the wheel comes to rest. For instance, British Pat. No. 966,955 shows a device in which pivotally movable members are provided radially on a wheel, with a tooth being formed at the end of each movable member such as to form a slot between each tooth and the wheel, the slot being varied in size in accordance with the movement of each pivoted member so as to automatically grip or release the strand.
Also known in the art is a mechanism in which mounting or dismounting procedure of the reel to or from the associated wheel maintains the strand gripping situation of the snaggers during the time when the reel is kept secured to the wheel, but such gripping of the snaggers on the strand is released when the reel is removed from the wheel. For instance, U.S. Pat. No. 3,695,528 discloses a snagger mechanism such that, when the reel is mounted in position on the associated wheel, each elastic member on the wheel is pressed by the axial movement of the reel to diminish the space between each snagger and the wheel to thereby grip the strand. According to this mechanism, gripping of the strand and release thereof are automatically accomplished in accordance with the mounting and dismounting of the reel relative to the associated wheel.
In any of these known mechanisms, however, it is difficult to effect automatic gripping and release under all circumstances. It is practically impossible to use such mechanisms for high speed operations where the take-up speed exceeds 3,000 m/min. For instance, the device shown in British Pat. No. 966,955 can be adapted only in a take-up mechanism where a pair of reels are arranged on the same axis in side by side relation. It cannot be used where two reels designed to be rotatable at high speeds are arranged axially parallel to each other. Also, the radial arrangement of the pivotally movable members involves a danger since an excessively high centrifugal force could be produced at high rotation speeds. On the other hand, U.S. Pat. No. 3,695,528 discloses a structure in which the centrifugal force affecting the movable parts is all sustained by the fixed members, so there is a possibility that in this mechanism the engagement of the snaggers may be weakened by the centrifugal force, and there is also difficulty involved with respect to increasing the strand gripping force. It is therefore extremely difficult if not impossible, with such a mechanism, to effect successful shifting of the strand at high speeds.